What sun, sea and sand really do to your brain

Roger Highfield
18 January 2013

The Science Museum Group's Roger Highfield reveals all

You're lying on the beach, eyes clamped shut, thinking of absolutely nothing at all. And yet your brain is still burning as much energy as when it is fully active.

Your brain is energy-hungry and, even when you rest, consumes about one fifth of the calories you eat. In 1929 Hans Berger discovered that the brain remains active, even when it is in neutral, by measuring electrical activity along the scalp, using a method known as electroencephalography (EEG).

However, it wasn't until the mid-1990s that body scanner studies by Marcus Raichle and Gordon Shulman of Washington University, St Louis and others revealed that when the mind is disengaged, a system is turned on — the 'default network'.

Unusually, this constellation of brain areas dims when you concentrate. Measurements of metabolic activity show that parts of this network devour one third more calories, gram for gram, than nearly any other brain area. When you are lying down, eyes shut, it burns more oxygen than your beating heart.

What's it doing? The network is connected to the hippocampus, which stores autobiographical memories, so it could be collating and weaving them into a narrative. It's also linked with thinking about the future and gauging others' perspectives.

The same pathways may also be involved in creativity by helping us to weigh up and link disparate concepts. There is evidence, from a study by Shelley Carson at Harvard University, that we are more open to novel ideas when our minds are allowed to wander.

So after a lazy holiday on the beach, remember to tell your boss the truth: every minute the sun shone, you were in the grip of frenzied brainstorming.

Roger Highfield is the Director of External Affairs at the Science Museum Group.

Read more: the joys of lying on a beach and six of the best beaches to laze on.